IT’S getting hard to be anonymous. To do just about anything in this world you have to prove who you are. Want to buy something or draw some cash? There’s a wodge of credit cards to lug around, and a plethora of four-digit PINs to remember. Even before stepping out of the front door you’ve got to find your driver’s licence or rail pass, perhaps even your passport.

In a few years, this plastic and paper baggage could be history. A single chip hidden in your cellphone will be all you need – a little treasure that holds your complete identity. But beware. Lose your phone, and your identity and your money go with it. The big question is whether people will be willing to trust so much to a sliver of silicon.

Inside every digital mobile phone is a SIM card. SIM stands for subscriber information module, and the chip embedded in the SIM card is what makes the mobile yours. For now, the SIM just identifies you to the phone system, and maybe holds details of your favourite phone numbers. In future it could identify you to everyone who needs to know who you are.